Clinicopathological analysis of a composite lymphoma containing both T‐ and B‐cell lymphomas

Composite lymphomas (CLs) have been reported in 1–4.7% of all lymphomas, however, CLs containing both T‐ and B‐cell lymphomas (CTBLs) are very rare. Here, we examined the clinical and pathological features of 29 CTBLs. These CTBLs included 21 patients with angioimmunoblastic T‐cell lymphoma (AITL) and diffuse large B‐cell lymphoma (DLBCL), two with adult T‐cell leukemia/lymphoma and DLBCL, one with AITL and Follicular lymphoma, one with Lennert lymphoma and DLBCL, one with subcutaneous panniculitis‐like T‐cell lymphoma and DLBCL, one with peripheral T‐cell lymphoma (PTCL) and DLBCL, one with cutaneous T‐cell lymphoma and DLBCL, and one with PTCL and chronic lymphocytic leukemia. Eighteen of 27 patients (67%) were shown to be Epstein‐Barr virus (EBV)‐encoded RNA‐positive in their B‐cell lymphoma component. T‐cell and B‐cell clonality were confirmed by flow cytometry, Southern blot analysis, and/or polymerase chain reaction (PCR). Using Southern blot analysis, clonal immunoglobulin heavy chain (IgH) and T‐cell receptor (TCR) rearrangements were detected in 11 of 21 and 15 of 24 cases, respectively. Using PCR analysis, clonal IgH and TCR rearrangements were detected in 7 of 8 and 7 of 7 Southern blot‐negative cases, respectively. Our results suggested that PCR analysis was useful in diagnosing CTBL.